U.S. patent application number 17/086095 was filed with the patent office on 2022-05-05 for methods and systems for an engine.
The applicant listed for this patent is Ford Global Technologies, LLC. Invention is credited to Xiaogang Zhang.
Application Number | 20220136420 17/086095 |
Document ID | / |
Family ID | 1000005209727 |
Filed Date | 2022-05-05 |
United States Patent
Application |
20220136420 |
Kind Code |
A1 |
Zhang; Xiaogang |
May 5, 2022 |
METHODS AND SYSTEMS FOR AN ENGINE
Abstract
Methods and systems are provided for an engine of a vehicle. In
one example, a method includes activating a heater in response to
an engine start request when a catalyst temperature is less than a
threshold temperature.
Inventors: |
Zhang; Xiaogang; (Novi,
MI) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Ford Global Technologies, LLC |
Dearborn |
MI |
US |
|
|
Family ID: |
1000005209727 |
Appl. No.: |
17/086095 |
Filed: |
October 30, 2020 |
Current U.S.
Class: |
60/284 |
Current CPC
Class: |
F01N 2390/02 20130101;
F01N 2900/1602 20130101; F01N 3/2013 20130101; F01N 2240/16
20130101; F01N 3/225 20130101 |
International
Class: |
F01N 3/20 20060101
F01N003/20 |
Claims
1. A method comprising: pumping heated air between a first catalyst
and a second catalyst in response to an engine cold start request,
wherein pumping heated air comprises flowing air back and forth
from the first catalyst and the second catalyst; wherein a heating
device is arranged between the first catalyst and the second
catalyst; and wherein a first gap is arranged between the first
catalyst and the heating device and a second gap is arranged
between the second catalyst and the heating device.
2. The method of claim 1, further comprising cranking an engine
unfueled in response to the engine cold start request.
3-4. (canceled)
5. The method of claim 1, further comprising supplying electrical
energy to the heating device.
6. The method of claim 1, further comprising sensing a temperature
of the first catalyst in response to the engine cold start request
via a temperature sensor prior to pumping heated air, wherein the
temperature is less than a threshold temperature.
7. A system, comprising: an engine; an aftertreatment device
comprising a first catalyst, a second catalyst, a sensor, and an
electric heater arranged in a housing, wherein the electric heater
is arranged between the first catalyst and the second catalyst and
wherein the sensor is arranged adjacent to an upstream face of the
first catalyst; and a controller comprising computer-readable
instructions stored on non-transitory memory thereof that when
executed enable the controller to: sense a temperature of the first
catalyst in response to an engine start request; crank the engine
and activate the electric heater in response to the temperature
being less than a threshold temperature; and open all intake valves
and exhaust valves of the engine when the engine is cranked;
wherein opening the intake and exhaust valves oscillates intake
gases in an intake system and exhaust gases in an exhaust system;
and wherein a first gap is arranged between the first catalyst and
the electric heater and a second gap is arranged between the second
catalyst and the electric heater.
8. The system of claim 7, wherein the instructions further enable
the controller to block spark to the engine when the engine is
cranked.
9. The system of claim 7, wherein the instructions further enable
the controller to crank the engine unfueled.
10-11. (canceled)
12. The system of claim 7, wherein the instructions further enable
the controller to deactivate the electric heater in response to the
temperature being greater than or equal to the threshold
temperature.
13. The system of claim 12, wherein the instructions further enable
the controller to fuel the engine and provide spark to the
engine.
14. (canceled)
15. The system of claim 7, wherein the instructions further enable
the controller to provide fuel and spark to the engine in response
to the temperature being greater than or equal to the threshold
temperature, and wherein the electric heater is not activated in
response to the temperature being greater than or equal to the
threshold temperature.
16. A method for operating an engine, comprising: rotating the
engine with each exhaust valve and intake valve of each engine
cylinder open in response to a request to start the engine; and
activating a heater in an exhaust system in response to the request
to start the engine; wherein the heater is arranged between a first
catalyst and a second catalyst; and wherein a first gap is arranged
between the first catalyst and the heating device and a second gap
is arranged between the second catalyst and the heating device.
17. The method of claim 16, further comprising sensing a
temperature of a catalyst arranged upstream of the heater relative
to a direction of gas flow in the exhaust system being less than a
light-off temperature prior to rotating the engine.
18. The method of claim 16, further comprising adjusting intake
valve and exhaust valve lift to equalize flow oscillations in the
exhaust system and an intake system.
19. The method of claim 16, further comprising deactivating the
heater in response to a temperature of a catalyst being greater
than or equal to a light-off temperature.
20. The method of claim 16, wherein rotating further comprises
rotating the engine unfueled as gases in the exhaust system
oscillate between a first catalyst and a second catalyst, wherein
the heater is arranged between the first catalyst and the second
catalyst.
Description
FIELD
[0001] The present description relates generally to methods and
systems for an engine during a cold-start.
BACKGROUND/SUMMARY
[0002] Emissions regulations continue to become increasingly
stringent in an effort to curb human contributions to global
warming. For vehicles comprising an internal combustion engine, a
large source of emissions includes cold-starts where an engine
operating temperature is less than a desired temperature. During
the cold-start, hydrocarbon emissions may be elevated due to poor
evaporation, fuel film formation, and insufficient time for the
liquid film to evaporate during intake and compression strokes. The
film may evaporate during an exhaust stroke, resulting in high
hydrocarbon emissions to an exhaust system where catalysts may not
yet be lit-off to oxidize the hydrocarbons.
[0003] Other examples of addressing hydrocarbon emissions include
electric heaters and complex coolant arrangements. However, these
arrangements may increase manufacturing costs while also demanding
pumps and valves to operate based on complex methods. Additionally,
while heating the catalysts in the exhaust passage with an electric
heater allows oxidation of the hydrocarbons, the issue with reduced
hydrocarbon combustion is not cured, resulting in increased fuel
consumption during the cold-start due to the engine still
combusting prior to the catalyst reaching a light-off
temperature.
[0004] In one example, the issues described above may be addressed
by a method comprising pumping heated air between a first catalyst
and a second catalyst in response to an engine start request. In
this way, the catalysts and the engine are heated more quickly.
[0005] As one example, a temperature of the first catalyst is less
than a light-off temperature when the engine start is requested.
Air in an exhaust system may be heated via an electric heater
arranged between the first catalyst and the second catalyst to
decrease a cold-start duration. The air is pumped via cranking of
the engine while intake and exhaust valves of the engine are open
to oscillate air in the intake and exhaust systems. The engine is
unfueled during this time, thereby delaying emission production
until the first catalyst is lit-off.
[0006] It should be understood that the summary above is provided
to introduce in simplified form a selection of concepts that are
further described in the detailed description. It is not meant to
identify key or essential features of the claimed subject matter,
the scope of which is defined uniquely by the claims that follow
the detailed description. Furthermore, the claimed subject matter
is not limited to implementations that solve any disadvantages
noted above or in any part of this disclosure.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] FIG. 1 illustrates a schematic of an engine included in a
hybrid vehicle.
[0008] FIG. 2 illustrates an example operation of a plurality of
cylinder during an engine start request.
[0009] FIGS. 3A and 3B illustrate an example air flow through an
aftertreatment device during the engine start request.
[0010] FIG. 4 illustrates a method for executing an engine start in
response to an engine start request when a catalyst temperature is
less than a threshold temperature.
[0011] FIG. 5 illustrates an example engine operating sequence
illustrating engine conditions in response to an engine start
request when a catalyst temperature is less than a light-off
temperature.
DETAILED DESCRIPTION
[0012] The following description relates to systems and methods for
an engine. In one example, the engine is an engine of a hybrid
vehicle, as illustrated in FIG. 1. An exhaust system of the engine
may comprise an electric heater positioned adjacent to a catalyst.
The engine may be operated during certain conditions to pump gases
back and forth through the catalyst and the electric heater to heat
the catalyst more quickly. An example of the gases flowing through
the heater and the catalyst is illustrated in FIGS. 3A and 3B. To
pump the gases, the engine may be cranked while unfueled. Intake
and exhaust valves of the engine may be opened to reduce pumping
losses while displacing gases in the intake and exhaust systems, as
shown in FIG. 2. A method for operating the engine in response to a
start request during cold-start conditions is illustrated in FIG.
4. FIG. 5 illustrates an example engine operating sequence
illustrating engine conditions in response to an engine start
request when a catalyst temperature is less than a light-off
temperature.
[0013] FIGS. 1-3B show example configurations with relative
positioning of the various components. If shown directly contacting
each other, or directly coupled, then such elements may be referred
to as directly contacting or directly coupled, respectively, at
least in one example. Similarly, elements shown contiguous or
adjacent to one another may be contiguous or adjacent to each
other, respectively, at least in one example. As an example,
components laying in face-sharing contact with each other may be
referred to as in face-sharing contact. As another example,
elements positioned apart from each other with only a space
there-between and no other components may be referred to as such,
in at least one example. As yet another example, elements shown
above/below one another, at opposite sides to one another, or to
the left/right of one another may be referred to as such, relative
to one another. Further, as shown in the figures, a topmost element
or point of element may be referred to as a "top" of the component
and a bottommost element or point of the element may be referred to
as a "bottom" of the component, in at least one example. As used
herein, top/bottom, upper/lower, above/below, may be relative to a
vertical axis of the figures and used to describe positioning of
elements of the figures relative to one another. As such, elements
shown above other elements are positioned vertically above the
other elements, in one example. As yet another example, shapes of
the elements depicted within the figures may be referred to as
having those shapes (e.g., such as being circular, straight,
planar, curved, rounded, chamfered, angled, or the like). Further,
elements shown intersecting one another may be referred to as
intersecting elements or intersecting one another, in at least one
example. Further still, an element shown within another element or
shown outside of another element may be referred as such, in one
example. It will be appreciated that one or more components
referred to as being "substantially similar and/or identical"
differ from one another according to manufacturing tolerances
(e.g., within 1-5% deviation).
[0014] FIG. 1 shows a schematic depiction of a hybrid vehicle
system 6 that can derive propulsion power from engine system 8
and/or an on-board energy storage device. An energy conversion
device, such as a generator, may be operated to absorb energy from
vehicle motion and/or engine operation, and then convert the
absorbed energy to an energy form suitable for storage by the
energy storage device.
[0015] Engine system 8 may include an engine 10 having a plurality
of cylinders 30. Engine 10 includes an engine intake 23 and an
engine exhaust 25. Engine intake 23 includes an air intake throttle
62 fluidly coupled to the engine intake manifold 44 via an intake
passage 42. Air may enter intake passage 42 via air filter 52.
Engine exhaust 25 includes an exhaust manifold 48 leading to an
exhaust passage 35 that routes exhaust gas to the atmosphere.
Engine exhaust 25 may include one or more emission control devices
70 mounted in a close-coupled position or in a far underbody
position. The one or more emission control devices may include a
three-way catalyst, lean NOx trap, diesel particulate filter,
oxidation catalyst, etc. It will be appreciated that other
components may be included in the engine such as a variety of
valves and sensors, as further elaborated in herein. In some
embodiments, wherein engine system 8 is a boosted engine system,
the engine system may further include a boosting device, such as a
turbocharger (not shown).
[0016] Vehicle system 6 may further include control system 14.
Control system 14 is shown receiving information from a plurality
of sensors 16 (various examples of which are described herein) and
sending control signals to a plurality of actuators 81 (various
examples of which are described herein). As one example, sensors 16
may include exhaust gas sensor 126 located upstream of the emission
control device, temperature sensor 128, and pressure sensor 129.
Other sensors such as additional pressure, temperature, air/fuel
ratio, and composition sensors may be coupled to various locations
in the vehicle system 6. As another example, the actuators may
include the throttle 62.
[0017] Controller 12 may be configured as a conventional
microcomputer including a microprocessor unit, input/output ports,
read-only memory, random access memory, keep alive memory, a
controller area network (CAN) bus, etc. Controller 12 may be
configured as a powertrain control module (PCM). The controller may
be shifted between sleep and wake-up modes for additional energy
efficiency. The controller may receive input data from the various
sensors, process the input data, and trigger the actuators in
response to the processed input data based on instruction or code
programmed therein corresponding to one or more routines.
[0018] In some examples, hybrid vehicle 6 comprises multiple
sources of torque available to one or more vehicle wheels 59. In
other examples, vehicle 6 is a conventional vehicle with only an
engine, or an electric vehicle with only electric machine(s). In
the example shown, vehicle 6 includes engine 10 and an electric
machine 51. Electric machine 51 may be a motor or a
motor/generator. A crankshaft of engine 10 and electric machine 51
may be connected via a transmission 54 to vehicle wheels 59 when
one or more clutches 56 are engaged. As shown, a drive axle 53 may
be used to transfer power from the transmission 54 to the wheels
59, in one example. The drive axle 53 is a rear axle, in one
example. In the depicted example, a first clutch 56 is provided
between a crankshaft and the electric machine 51, and a second
clutch 56 is provided between electric machine 51 and transmission
54. Controller 12 may send a signal to an actuator of each clutch
56 to engage or disengage the clutch, so as to connect or
disconnect crankshaft from electric machine 51 and the components
connected thereto, and/or connect or disconnect electric machine 51
from transmission 54 and the components connected thereto.
Transmission 54 may be a gearbox, a planetary gear system, or
another type of transmission. The powertrain may be configured in
various manners including as a parallel, a series, or a
series-parallel hybrid vehicle.
[0019] Electric machine 51 receives electrical power from a
traction battery 61 to provide torque to vehicle wheels 59.
Electric machine 51 may also be operated as a generator to provide
electrical power to charge battery 61, for example during a braking
operation.
[0020] Turning now to FIG. 2, it shows an embodiment 200 of the
plurality of cylinders 30 being operated during a cold-start. As
such, the plurality of cylinders 30 are used in engine 10 of FIG.
1. Components previously introduced are similarly numbered in this
figure and subsequent figures.
[0021] The plurality of cylinders 30 comprises four cylinders in
the example of FIG. 2. However, it will be appreciated that more
than four or fewer than four cylinders may be used without
departing from the scope of the present disclosure. The plurality
of cylinders 30 comprises a first cylinder 202, a second cylinder
212, a third cylinder 222, and a fourth cylinder 232. In the
example of FIG. 2, each of the plurality of cylinders 30 is
identical.
[0022] The first cylinder 202 comprises an intake valve 204, an
exhaust valve 206, and a piston 208. The intake valve 204 may be
actuated via an intake actuator 205 and the exhaust valve 206 may
be actuated via an exhaust actuator 207. In one example, the intake
actuator 205 and the exhaust actuator 207 may be hydraulic lash
adjusters or other similar types of valve adjusters that may adjust
positions of the intake and exhaust valve to fully closed
positions, fully open positions (e.g., as illustrated in FIG. 2),
and positions therebetween.
[0023] The second cylinder 212 comprises an intake valve 214, an
exhaust valve 216, and a piston 218. The intake valve 214 may be
actuated via an intake actuator 215 and the exhaust valve 216 may
be actuated via an exhaust actuator 217. In one example, the intake
actuator 215 and the exhaust actuator 217 may be a type of adjuster
similar to the intake actuator 205 and exhaust actuator 207.
[0024] The third cylinder 222 comprises an intake valve 224, an
exhaust valve 226, and a piston 228. The intake valve 224 may be
actuated via an intake actuator 225 and the exhaust valve 226 may
be actuated via an exhaust actuator 227. In one example, the intake
actuator 225 and the exhaust actuator 227 may be a type of adjuster
similar to the intake actuator 205 and the exhaust actuator
207.
[0025] The fourth cylinder 232 comprises an intake valve 234, an
exhaust valve 236, and a piston 238. The intake valve 234 may be
actuated via an intake actuator 235 and the exhaust valve 236 may
be actuated via an exhaust actuator 237. In one example, the intake
actuator 235 and the exhaust actuator 237 may be a type of adjuster
similar to the intake actuator 205 and the exhaust actuator
207.
[0026] In the example of FIG. 2, the intake valves and the exhaust
valves of each engine cylinder of the plurality of cylinders are
illustrated in fully open positions. In one example, the operation
illustrated in FIG. 2 occurs during an engine cold-start. In
response to a start-request occurring while an engine temperature
corresponds to a cold-start, the controller may signal to block
fueling to the plurality of cylinders 30. The controller may then
signal to a starter motor or other device to crank the plurality of
cylinders 30 such that intake gases 242 and exhaust gases 244 may
flow therein. More specifically, the pistons may pump intake and
exhaust gases entering the combustion chambers of the cylinders.
The pumping may generate an oscillating motion of intake gases in
the intake system and exhaust gases in the exhaust system.
[0027] An electric heater may be arranged in an aftertreatment
housing, as illustrated in the embodiment of FIGS. 3A and 3B,
wherein the electric heater is arranged between a first catalyst
and a second catalyst. As the engine cranks during the cold-start,
exhaust gases may flow back and forth between the first catalyst
and the second catalyst. As such, exhaust gases may flow across the
electric heater as it oscillates between the first catalyst and the
second catalyst. By doing this, a light-off temperature of the
first catalyst and the second catalyst may be quickly reached,
thereby decreasing emissions and fuel consumption.
[0028] Turning now to FIGS. 3A and 3B, they show embodiments 300
and 350 illustrating exhaust gas flow through the aftertreatment
device 70 of the engine 10 during a cold-start, respectively. As
illustrated, exhaust gas flows in a first direction 302 in the
aftertreatment device 70 in the embodiment 300 and in a second
direction 304, opposite the first direction 302, in the embodiment
350.
[0029] The aftertreatment device 70 comprises a first catalyst 312
and a second catalyst 314. The first catalyst 312 and the second
catalyst 314 may be arranged within a single housing 310 of the
aftertreatment device 70. In one example, the first catalyst 312 is
arranged upstream of the second catalyst 314 relative to a
direction of exhaust gas flow from the engine 10 to the
aftertreatment device 70.
[0030] The first catalyst 312 and the second catalyst 314 may be
identical in size, shape, and composition. In one example, the
first catalyst 312 and the second catalyst 314 are an oxidation
catalyst or other catalyst configured to oxidize hydrocarbons. In
some examples, additionally or alternatively, the first catalyst
312 and/or the second catalyst 314 may comprise a particulate
filter.
[0031] An electric heater 322 is arranged within the housing 310
between the first catalyst 312 and the second catalyst 314. A first
gap 332 is arranged between the electric heater 322 and the first
catalyst 312. A second gap 334 is arranged between the electric
heater 322 and the second catalyst 314. The first gap 332 may be
identical in size to the second gap 334. Additionally or
alternatively, a size of the first gap 332 may be greater than or
less than a size of the second gap 334.
[0032] In one embodiment, electric power is used to crank the
engine until it reaches a threshold revolution per minute. The
threshold revolution per minute may be greater than 1,000. In one
example, the threshold revolution per minute is 1,250. The intake
and exhaust valves are opened in the plurality of cylinders to
decrease pumping losses in the engine. During the cold-start when
the engine is being cranked, spark and fuel injections are blocked,
thereby preventing combustion. Intake gases flowing into the
cylinders flow back to the intake manifold and exhaust gases
flowing into the cylinders flow back to the exhaust manifold 48. As
such, oscillating flow patterns occur in both the intake and
exhaust systems.
[0033] The vehicle, which may be configured as a hybrid electric
vehicle and/or a plug-in hybrid electric vehicle, comprises the
first catalyst 312 (e.g., an upstream catalyst) and the second
catalyst 314 (e.g., a downstream catalyst) configured to reduce
hydrocarbons, carbon monoxide, and NO.sub.x emissions. Substrates
of the catalysts may treat a majority of emissions upon reaching a
light-off temperature. In one example, the light-off temperature
may be greater than 200.degree. C. In one example, the light-off
temperature is equal to 300.degree. C. The electric heater 322 is
configured to accelerate a heating of the first catalyst 312 and
the second catalyst 314 during the cold-start. A temperature sensor
316, which is arranged within the first catalyst 312, is configured
to determine a temperature of the first catalyst 312. In one
example, the temperature sensor 316 is arranged adjacent to an
upstream surface of the first catalyst 312. In one example, the
temperature sensor 316 is a high-temperature infrared sensor.
[0034] The electric heater 322 may be heated to an upper
temperature (e.g., 1200.degree. C.). In one example, a temperature
of the electric heater 322 may be adjusted based on a difference
between a current first catalyst temperature and the light-off
temperature. As the difference increases, the temperature of the
electric heater 322 may also increase. As the difference decreases,
the temperature of the electric heater 322 may also decrease, which
may decrease a charge consumption of the battery. By adjusting the
temperature of the electric heater 322, a temperature of the
exhaust gases may also be adjusted.
[0035] The exhaust gases flow across the electric heater 322,
through the first catalyst 312, and into the exhaust manifold 48,
thereby heating the exhaust system. During a subsequent stroke, the
exhaust gases may be pushed from the exhaust manifold 48, through
the first catalyst 312, through the electric heater 322, and into
the second catalyst 314. The exhaust gases may continue to flow in
this pattern until the first catalyst 312 is lit-off and the engine
begins receiving fuel and spark. In some examples, a compression
ratio of the engine may be adjusted to adjust a flow pattern of the
exhaust gases. For example, the compression ratio may be decreased
to shorten a piston stroke length, which may decrease an exhaust
gas displacement volume. As such, the exhaust gases may be
configured to oscillate only between the first catalyst 312 and the
second catalyst 314 without reaching the exhaust manifold 48.
[0036] Turning now to FIG. 4, it shows a method 400 for operating
the electric heater and engine during a cold-start. Instructions
for carrying out method 400 may be executed by a controller based
on instructions stored on a memory of the controller and in
conjunction with signals received from sensors of the engine
system, such as the sensors described above with reference to FIG.
1. The controller may employ engine actuators of the engine system
to adjust engine operation, according to the method described
below.
[0037] The method 400 begins at 402, which includes determining,
estimating, and/or measuring current operating parameters. Current
engine operating parameters may include but are not limited to one
or more of a manifold pressure, a throttle position, an engine
temperature, an engine speed, a vehicle speed, and an air/fuel
ratio.
[0038] The method 400 may proceed to 404, which includes
determining if an engine-start is requested during cold-start
conditions. The engine-start may be requested in response to an
ignition key being turned, a button being depressed, and the like.
A cold-start may be occurring when an engine temperature is less
than a desired operating temperature and/or if a catalyst
temperature is less than a light-off temperature. If the cold-start
is not occurring, then the method 400 proceeds to 406, which
includes maintaining current operating parameters and does not
activate the electric heater. If an engine start was requested,
then the engine is fueled and receives spark in order to
combust.
[0039] If the cold-start is occurring, then the method 400 proceeds
to 408, which includes not fueling and/or sparking the engine. As
such, combustion in the engine is blocked in response to the start
request that would generate a cold-start.
[0040] The method 400 proceeds to 410, which includes opening the
intake and exhaust valves. By opening the intake and the exhaust
valves, pumping losses in the engine may be reduced when the engine
is cranked.
[0041] The method 400 proceeds to 412, which includes cranking the
engine. The engine may be cranked via electrical energy supplied
from a battery to a starter motor or other device configured to
rotate the pistons of the engine. With the intake and exhaust
valves open, pumping losses are reduced as gases in the intake
system and the exhaust system are displaced via the engine. Said
another way, the engine is operated as a pump, thereby oscillating
intake gases in the intake system and exhaust gases in the exhaust
system. In one example, the intake gases and the exhaust gases are
ambient air which may be mixed with residual combustion gases from
a previous drive cycle back-filled in the intake and exhaust
systems.
[0042] The method 400 proceeds to 414, which includes activating an
electric heater. The electric heater may be heater to a threshold
electric heater temperature. In one example, the threshold electric
heater temperature is a fixed temperature, wherein the fixed
temperature is greater than 1000.degree. C. Additionally or
alternatively, the electric heater may be heated to a temperature
in a temperature range, wherein the temperature range is between
600 to 1500.degree. C. In one example, the electric heater is
heated to a higher temperature of the temperature range as a
difference between a light-off temperature of the first catalyst
and a current temperature of the first catalyst increases. The
electric heater may be heated to a lower temperature of the
temperature range as the difference decreases, which may decrease
electrical energy consumption and further decrease emissions.
[0043] Additionally or alternatively, the vehicle operator may
provide an input regarding a desired rate of a first catalyst
warm-up duration. For example, a display device in the vehicle may
prompt the vehicle operator to select a rapid first catalyst
warm-up duration or a slower first catalyst warm-up duration. The
rapid first catalyst warm-up duration may consume a greater amount
of electrical energy while heating the first catalyst more quickly
than the slower first catalyst warm-up duration, which reduced
energy consumption. The vehicle operator may be presented with
these options and benefits and select a warm-up type.
[0044] The method 400 proceeds to 416, which may include
determining if a catalyst temperature is greater than or equal to a
threshold temperature. In one example, the threshold temperature is
equal to a light-off temperature of the first catalyst. If the
catalyst temperature is not greater than or equal to the threshold
temperature, then the method 400 proceeds to 418, which includes
continuing to electrically heating the catalysts via the electric
heater. The method 400 may further comprise continually monitoring
the first catalyst temperature based on feedback from the
temperature sensor.
[0045] If the catalyst temperature is greater than or equal to the
catalyst temperature, then the method 400 proceeds to 420, which
includes deactivating the electric heater. As such, electrical
energy is no longer consumed to power the electric heater.
[0046] The method 400 proceeds to 422, which includes fueling and
sparking the engine. Engine combustion is initiated and the
combustion gases may be treated at the first catalyst.
[0047] Turning now to FIG. 5, it shows a graph 500 illustrating an
example engine operating sequence of an engine start request when a
catalyst temperature is less than a light-off temperature. Plot 510
illustrates if an engine start is requested. Plot 520 illustrates a
catalyst temperature and dashed line 522 illustrates a light-off
temperature. In one example, the light-off temperature is equal to
300.degree. C. Plot 530 illustrates an exhaust gas flow direction.
The exhaust gas may flow in a first direction or in a second
direction. The first direction may be from the engine to a tailpipe
and the second direction may be from the tailpipe to the engine.
Plot 540 illustrates an electric heater activity. Plot 550
illustrates if an engine is fueled. Plot 560 illustrates if the
engine is sparked. Time increases from a left to a right side of
the figure.
[0048] Prior to t1, an engine start is requested (plot 510). During
the engine start request, the catalyst temperature (plot 520) is
less than a light-off temperature (dashed line 522). The engine is
not yet fueled (plot 550) and is not yet sparked (plot 560). The
electric heater is not activated (plot 540). There is no exhaust
gas flow direction as a force is not applied to the exhaust gas
(plot 530).
[0049] At t1, the electric heater is activated and the exhaust gas
flow direction begins to oscillate between the first direction and
the second direction as the engine is cranked. Between t1 and t2,
the catalyst temperature increases from a relatively low
temperature toward the light-off temperature via gases in the
exhaust passage oscillating from the catalyst to the electric
heater. That is to say, the exhaust gases may flow through the
catalyst and through the electric heater, continuously, which may
accelerate warm-up of the catalyst relative to previous examples
where the engine is combusted during cranking or where the electric
heater directly heats the catalyst. Furthermore, by delaying
combustion, emissions are reduced during the cold-start.
[0050] At t2, the catalyst temperature is equal to a light-off
temperature. As such, the engine is fueled and sparked, resulting
in combustion. The electric heater is deactivated as the catalyst
temperature is sufficiently high and able to treat a desired amount
of emissions. After t2, the catalyst temperature continue to
increase as exhaust gases flowing in only the first direction flow
therethrough as the engine combusts.
[0051] In this way, an electric heater is configured to rapidly
heat one or more catalysts arranged in an aftertreatment housing.
Gases in an exhaust system are oscillated between the catalysts via
an engine being unfueled and not receiving spark. The gases flow
across the electric heater and through the one or more catalysts.
The technical effect of not combusting the engine during the
cold-start as the catalysts are heated is to reduce emissions and
block formation of fuel film on surfaces of the combustion chamber.
By doing this, the catalyst may be quickly heated and the engine
may begin combustion, wherein the catalyst may treat emissions from
the engine in an efficient manner.
[0052] An embodiment of a method comprises pumping heated air
between a first catalyst and a second catalyst in response to an
engine start request.
[0053] A first example of the method further includes where
cranking an engine unfueled in response to the engine start
request.
[0054] A second example of the method, optionally including the
first example, further includes where pumping heated air comprises
flowing air back and forth from the first catalyst and the second
catalyst, wherein a heating device is arranged between the first
catalyst and the second catalyst.
[0055] A third example of the method, optionally including one or
more of the previous examples, further includes where a first gap
is arranged between the first catalyst and the heating device and a
second gap is arranged between the second catalyst and the heating
device.
[0056] A fourth example of the method, optionally including one or
more of the previous examples, further includes where supplying
electrical energy to the heating device.
[0057] A fifth example of the method, optionally including one or
more of the previous examples, further includes where sensing a
temperature of the first catalyst in response to the engine start
request via a temperature sensor prior to pumping heated air,
wherein the temperature is less than a threshold temperature.
[0058] An embodiment of a system comprises an engine, an
aftertreatment device comprising a first catalyst, a second
catalyst, and an electric heater arranged in a housing, wherein the
electric heater is arranged between the first catalyst and the
second catalyst, and a controller comprising computer-readable
instructions stored on non-transitory memory thereof that when
executed enable the controller to sense a temperature of the first
catalyst in response to an engine start request, and crank the
engine and activate the electric heater in response to the
temperature being less than a threshold temperature.
[0059] A first example of the system further includes where the
instructions further enable the controller to block spark to the
engine when the engine is cranked.
[0060] A second example of the system, optionally including the
first example, further includes where the instructions further
enable the controller to crank the engine unfueled.
[0061] A third example of the system, optionally including one or
more of the previous examples, further includes where a first gap
is arranged between the first catalyst and the electric heater and
a second gap is arranged between the second catalyst and the
electric heater.
[0062] A fourth example of the system, optionally including one or
more of the previous examples, further includes where a temperature
sensor arranged adjacent to an upstream face of the first
catalyst.
[0063] A fifth example of the system, optionally including one or
more of the previous examples, further includes where the
instructions further enable the controller to deactivate the
electric heater in response to the temperature being greater than
or equal to the threshold temperature.
[0064] A sixth example of the system, optionally including one or
more of the previous examples, further includes where the
instructions further enable the controller to fuel the engine and
provide spark to the engine.
[0065] A seventh example of the system, optionally including one or
more of the previous examples, further includes where the
instructions further enable the controller to open intake valves
and exhaust valves of the engine when the engine is cranked.
[0066] An eighth example of the system, optionally including one or
more of the previous examples, further includes where the
instructions further enable the controller to provide fuel and
spark to the engine in response to the temperature being greater
than or equal to the threshold temperature, and wherein the
electric heater is not activated in response to the temperature
being greater than or equal to the threshold temperature.
[0067] An embodiment of a method for operating an engine, comprises
rotating the engine with exhaust and intake valves of each engine
cylinder open in response to a request to start the engine and
activating a heater in an exhaust system in response to the request
to start the engine.
[0068] A first example of the method further includes where sensing
a temperature of a catalyst arranged upstream of the heater
relative to a direction of gas flow in the exhaust system being
less than a light-off temperature prior to rotating the engine.
[0069] A second example of the method, optionally including the
first example, further includes where adjusting intake valve and
exhaust valve lift to equalize flow oscillations in the exhaust
system and an intake system.
[0070] A third example of the method, optionally including one or
more of the previous examples, further includes where deactivating
the heater in response to a temperature of a catalyst being greater
than or equal to a light-off temperature.
[0071] A fourth example of the method, optionally including one or
more of the previous examples, further includes where rotating
further comprises rotating the engine unfueled as gases in the
exhaust system oscillate between a first catalyst and a second
catalyst, wherein the heater is arranged between the first catalyst
and the second catalyst.
[0072] Note that the example control and estimation routines
included herein can be used with various engine and/or vehicle
system configurations. The control methods and routines disclosed
herein may be stored as executable instructions in non-transitory
memory and may be carried out by the control system including the
controller in combination with the various sensors, actuators, and
other engine hardware. The specific routines described herein may
represent one or more of any number of processing strategies such
as event-driven, interrupt-driven, multi-tasking, multi-threading,
and the like. As such, various actions, operations, and/or
functions illustrated may be performed in the sequence illustrated,
in parallel, or in some cases omitted. Likewise, the order of
processing is not necessarily required to achieve the features and
advantages of the example embodiments described herein, but is
provided for ease of illustration and description. One or more of
the illustrated actions, operations and/or functions may be
repeatedly performed depending on the particular strategy being
used. Further, the described actions, operations and/or functions
may graphically represent code to be programmed into non-transitory
memory of the computer readable storage medium in the engine
control system, where the described actions are carried out by
executing the computer-readable instructions in a system including
the various engine hardware components in combination with the
electronic controller.
[0073] It will be appreciated that the configurations and routines
disclosed herein are exemplary in nature, and that these specific
embodiments are not to be considered in a limiting sense, because
numerous variations are possible. For example, the above technology
can be applied to V-6, I-4, I-6, V-12, opposed 4, and other engine
types. The subject matter of the present disclosure includes all
novel and non-obvious combinations and sub-combinations of the
various systems and configurations, and other features, functions,
and/or properties disclosed herein.
[0074] As used herein, the term "approximately" is construed to
mean plus or minus five percent of the range unless otherwise
specified.
[0075] The following claims particularly point out certain
combinations and sub-combinations regarded as novel and
non-obvious. These claims may refer to "an" element or "a first"
element or the equivalent thereof. Such claims should be understood
to include incorporation of one or more such elements, neither
requiring nor excluding two or more such elements. Other
combinations and sub-combinations of the disclosed features,
functions, elements, and/or properties may be claimed through
amendment of the present claims or through presentation of new
claims in this or a related application. Such claims, whether
broader, narrower, equal, or different in scope to the original
claims, also are regarded as included within the subject matter of
the present disclosure.
* * * * *